.field-error {
  font-size: 0.9em;
  color: #d9534f;
  background-color: #f8d7da;
  border: 1px solid #f5c6cb;
  padding: 6px 10px;
  margin-top: 4px;
  border-radius: 4px;
  opacity: 0;
  max-height: 0;
  overflow: hidden;
  transition: opacity 0.3s ease, max-height 0.3s ease;
  line-height: 1.3;
}

.field-error.visible {
  opacity: 1;
  max-height: 100px;
}

.input-error {
  border-color: #d9534f !important;
  background-color: #fcebea;
  outline: none;
  transition: background-color 0.3s ease, border-color 0.3s ease;
}
#contact-form {
  margin: 0 auto;

  line-height: 1.6;
}

#contact-form label {
  display: block;
  font-weight: bold;
  margin-top: 1.2em;
}

#contact-form input[type="text"],
#contact-form input[type="email"],
#contact-form input[type="tel"],
#contact-form select,
#contact-form textarea {
  width: 100%;
  padding: 0.6em;
  margin-top: 0.3em;
  border: 1px solid #ccc;
  border-radius: 4px;
  font-size: 1em;
  box-sizing: border-box;
  transition: border-color 0.2s;
}

#contact-form input[type="checkbox"] {
  margin-right: 0.5em;
}

#contact-form textarea {
  min-height: 120px;
  resize: vertical;
}

#contact-form input[type="submit"] {
  margin-top: 1.5em;
  padding: 0.8em 2em;
  font-size: 1em;
  border: none;
  border-radius: 4px;
  background-color: #0073aa;
  color: #fff;
  cursor: pointer;
  transition: background-color 0.2s;
}

#contact-form input[type="submit"]:hover {
  background-color: #005f8d;
}

/* ===== バリデーション用スタイル（JSと連携） ===== */
input:invalid,
select:invalid,
textarea:invalid {
  border-color: #d33;
}

input:valid,
select:valid,
textarea:valid {
  border-color: #3c763d;
}

.error-message {
  color: #d33;
  font-size: 0.9em;
  margin-top: 0.2em;
  display: none;
}

.error-message.active {
  display: block;
}